[asterisk-users] which codec over iax => pstn

[Gordon Henderson]

On Wed, 20 Feb 2008, sean darcy wrote:

>> G711 needs about 80Kb/sec each way to work. (It's 64Kb/sec plus IP
>> overhead). GSM needs about 32Kb/sec (13Kb/sec plus IP overhead).
>>
> So with DSL 512kbs up and 3mbs down, plenty of room for G711.

Probably. I've found that it's not the absolute speed that matters, but 
the quality of your connectivity ISP that's as crucial. IN theory you can 
support 5 or 6 G711 calls over that link, but it will depend on your 
ISP, your router and what else you're doing on the link at the time.

> Of course, I could figure out how to configure QOS in iptables for
> asterisk, it'd be a lot better.

A lot better to do it on your router, then it'll shape everything else on 
your LAN, although you can only effectively shape outgoing traffic, but 
this is usually enough given that outgoing speed is much less than 
incoming. (unless your router is linux, in which case google for 
wondershaper which is a good place to start)

Gordon